Looking at the fastest bowler competition, I do not think this is the average speed. From the video, if you look at the position of the siding with the measuring speed, it is located where they release the ball and not after.
Also, if they measured the average, then all the people in the competition would be bowling full tosses to remove the massive slowdown when the ball hits the pitch. But you saw a couple short ones there too, which leads me to believe that it was in fact measured only out of the hand. Which, if true, shows how ridiculously overrated the speeds of the past were. That is, with the exception of Thommo, who knocked one through at almost 150kph despite being well past his fastest in 1979. I can see him doing 160kph at his absolute prime. It would also fit in with what we know about Imran (being sharp but not express), as he is shown in the mid-high eighties. For him to average mid eighties, the speed out of the hand would likely have to be 100mph+, considering the ball loses such a huge percentage after hitting the speed. And we're fairly sure that Imran wasn't 100mph+ express.
Anyone have documentation where they detail it?